Liner for bearings



Nbv. 30,1937. Q HARDER 2,100,314

LINER FOR BEARINGS Filed Nov. 5, 1934 5 lnrer'mefallic Compound Cd-Ag Mai-rix INVENTOR.

Oscar E fHarde/r BY W V ATTORNEYS.

Patented Nov. 193 7- UNITED STATES PATENT OFFICE LINER. FOB. BEARINGS Oscan E. Harder, Columbus, Ohio, assignor, by mesne assignments, to Federal-Mogufcorporation, Detroit, Mich, a corporation of Michi- I gall Application November 5, 1934, Serial No. 751,546 10 (Cl. 308-242) My invention relates to liners for bearings. It This application is a continuation in part of has to do particularly with a novel liner for bearmy application, Serial No. 732,181, filed June 23, lugs for rotating shafts designed to operate 3 and my app ca o S a o- 743. 74. underheavy loads and at high speeds, although filed September 13, 1934. i

it is not necessarily limited thereto. Under preferred conditions, where my bearing 5 The use of relatively soft metals or'alloys as material is to take the form of a binary alloy liners for bearings is old. One purpose of such of cadmium and silver, I preferably use in exuse is to provide, as a support for the shaft, a cess of 3 per cent silver, since my tests have contacting surface which will adequately supindicated that silver goes into solid solution with 10 port athardened steel shaft or the like and, at cadmium up to'approximately 3 per cent of the 10 the sametime, which will avoid scoring or sesilver, while the excess over and above the 3 per riously abrading the shaft as it rotates within cent of silver will form intermetallic compounds the bearing. of silver and ,cadmium which are dispersed The metals which have been most extensively throughout the alloy as small hard particles. In

used for this purpose .may be generally classed this way, I am able to produce a lining material 15 as tin-base and lead-base alloys. The tin-base for bearings wherein the solid solution of cadalloys are mainly composed of tin but usually mium and silver form the relatively soft but contain substantial percentages of copper and tough matrix, while the intermetallic compounds antimony, increasing in hardness as the con .of silver and cadmium" which are dispersed tents of copper and antimony are increased. throughout this matrix as small hard particles 20 The lead-base alloys are mainly composed of I serve to make the contact and directly carry the lead, but usually contain significant percentages load. of one or more of the metals, antimony, tin and By way of illustration, the accompanying .coppergwhich generally serve to harden the aldrawing shows a photomicrograph. taken at 1000 10y. diameters, wherein the alloy contains 3 per. cent 25 n addition to the tin-base and lead-base alby weight of silver and the balance cadmium. loys, other alloys are, to a lesser extent, in use From this drawing, it will be seen that the small as bearinglinings. These. include alloys consisthard particles of intermetallic compound appear ing of cadmium, zinc and antimony, alloys of as white spots 5, which are embedded in amacadmium and nickel, and alloys of cadmium and trix that is apparently made up of a cored struc- 30 copper. Lead,,hardened with one or more alkali ture. metals or alkaline e'arthmetals, such as sodium, In studying-lining materials made in accordcalcium, barium and lithium, has also been used ance with my invention, I have prepared alloys as a bearing lining. I of cadmium and silver containing varying silver It is more or less generally recognized in the contents up to 10 per cent, These alloys were 35 art that alloys which are desirable as lining prepared by fusion and casting and their hardmaterials for bearings should be composed of ness and microstructures were determined. The harder particles embedded in a relatively soft data obtained in this connection showed that matrix. The theory is that the harder particles the cast alloys increased in hardness as the silver 40 serve to make the contact and directly carry the content increased; and hardnesses of 38 to 55 40 load,'while the softer matrix permits the lining Brinell (500 kg. load) were obtained. The study material to conform to the pe Of e moving of these alloys further showed thatin the commember or shaft. positions containing approximately 3 per cent My invention contemplates the production of of silver and over the microstructure consisted a lining material for bearings wherein the priof t o, phases. These phases apparently com- 45 mary ingredients are cadmium and silver alloyed prised the soft matrix formed by solid solution to, form a relatively soft but tough matrix. Such of silver in cadmium and a number of relatively an l y may be formed either y fusion and small hard particles dispersed throughout such casting of the alloy metals or by electrodeposisoft matrix. The amount of harder particles intion. The proportions of these metals may vary creased as the silver content increased. 50 but I prefer that the cadium be the base metal By electrodeposition, with the use of independand that the silver be introduced in relatively ent soluble anodes of cadmium and silver and by small percentages. 1 preferably use from .10 the use of an alkaline cyanide bath, I have deto 15 per cent of silver, with the balance of the posited bearing lining alloys containing from alloy cadmium. 1,72 togQ percent of silver. At the present time,

- soft and that an alloy containing more than 15 per cent of silver is inclined to be brittle and costly. However, for some classes of bearing service, an alloy containing as low as .10 per cent of silver may be suitable and is Within the scope of my invention. As a matter of fact, the presence of, even as little as .10 per cent of silver in the alloy improves the casting qualities of the cadmium, making it lesssusceptible to oxidation and dressing. Likewise, even a small percentage of added silver increases the fluidity, raises the melting point and improves the strength and hardness of the alloy.

Binary alloys which I have made by electrodeposition show substantially the same microconstituents as cadmium-silver, alloysprepared by fusion and casting, although the shape and distribution'may be somewhat different. Likewise, the grain structure is somewhat finer.

' I have determined the hardness of cadmiumsilver alloys in the as-cast condition, because it is not convenient to make hardness tests on thin plates of these alloys as formed by electrodeposition. In series of tests to determine the effect of adding silver to cadmium on the hardness at room temperature and at elevated temperatures, the following results were obtained:

Brinell hardness at room and elevated temperature of some cadmium base alloys Composition Temperature Cadmium Silver Room 212 F. 390 F.

Percent Percent 98. 93 1. O7 29. 8 18. 2 7. 1 97. 9O 2. 1O 34. 4 18. 6 7. 4 97. 09 2. 91 36. 2 20. 9 9. 5 94. 94 5. 06 40 2 22. 8 10. 0

The following table shows the hardness of alloys containing 6.4 per cent and 8.0 per cent of silver, respectively, at temperatures of 70, 350, and 450 F. For comparison purposes, hardness tests on a babbitt containing 85 per cent tin, 7.5 per cent copper, and 7.5 per cent antimony have been included:

Comparison of hardness of cadmium-silver alloys 85% tin, 7.5% copper, 7.5% antimony.

It will be observed that the hardness of the softer of, the two cadmium-silver alloys is somewhat greater than this particular hard babbitt at a temperature of 70 F. It is also evident that increasing the silver content of these alloys increases the hardness. Alloys softer than these can be obtained by using lower silver, and harder alloys by using higher silver content. It will be noted that at the temperature of 450 F. the cadmium-silveralloys are much harder than the babbitt and that the babbitt is very low in hard ness at this temperature. Since the electrodeposited alloys have very fine structures, it is believed that their hardness will be at least as great as in the as-cast alloys of similar compositions.

In order to compare further the properties of the cadmium-silver alloys with babbitt, pounding tests have been made. It is known that in bearing service the bearing linings are subjected to more fail because of low resistance to pounding. The

or less of a pounding action and that some of them followingv table shows the results of tests on two cadmium-silver alloys in the cast condition and on three babbitts also in. the cast condition. The

results have been,reported in terms of the number Pounding tests on cadmium-silver alloys and on babbitts* 7 Material Composition 22g 2% Cadmiumsilver alloy. 93.6% Cd, 6.4% Ag 70 Cadmium alloy- 92.0% Cd, 8.0% Ag 125 90.0% Sn, 4.5% Cu, 4.5% Sb.-. 12 7.5% Sn, 4.0% Cu, 7.6% Sb-" 14 83.8% Sn, .5% Cu, 7.5% Sb... 33

Tests with 7.15-1b. hammer falling 2 in.

The data show that even the softer of the two cadmium-silver alloys containing only 6.4% silver required 70 blows to deform it 5 per cent, whereas the hardest of the babbitts required only 33 blows to deform it 5 per cent. These results show that the resistance to deformation in pounding is increased as the silver content of these alloys is increased. Thus, if I wish to use an alloy to have high conformability I use an alloy lower in silver content, and if I wish to 'have an alloy of high hardness andhigh resistance to pounding I use an alloy of higher silver content.

These alloys, both cast and electrodeposited, on steel, cast iron, copper and bronze, have been subjected to wear tests and to actual bearing tests. In tests with the Amsler wear testing machine, an alloy containing 6.4 per cent of silver was found to give good performance. This was also true of a specimen containing 8.0 per cent of silver. When tested at as high a pressure as 3,250 lbs. per sq. in.,'the bearings performed satis- 1 factorily without excessive wear and without wiping or seizing on the steel shaft on which they were run in contact. Babbitts in a similar test usually fall at pressures of 2,000 to 3,000 lbs, per

sq. in.

The most conclusive test to which these bearing linings have been subjected comprises using them in connecting rods in an automotive, engine under very severe service. These bearing linings, formed by electrodeposition, were applied to backs of argentiierous copper, the lining being only 0.004 to 0.005 in. in thickness. In one series of tests three connectir g rod bearings lined with alloys containing 11.7, 11.0 and 5.6 per cent of silver were used. These bearings were run-in by starting the engine without a load at relatively low speed, gradually increasing the speed to about 3,000 R. P. M. over a period of about 30 hours. Afterwards, these bearings were subjected to the test which consisted of loading the engine and running it at full throttle at about 3,100 B. P. M. for a total period of 30 hours. The bearings formance.

- ning-in the'bearings as described above and then running 50 hours at full throttle under load. Three commercial babbitt bearings were run for comparison. The advantages noted in the cadmiuxn-silver alloys may be listed as follows:

Lower rate of wear was observed in the cadmium-silver linings. Cadmium-silver alloy linings containing 7.5 per cent of silver, after running 30 hours for running-in and 50 hours with the engine loaded while operating at full throttle, showed practically no wear. They had bright polished surfaces when removed from the engine,

whereas babbitt bearings used in the engine at the same time and for the same periods were dark andcoated, as wellas being materially pitted; As other advantages of the cadmium-silver alloys, I have noted that they do not, within the range I studied, show the tendency to flow under operating conditions, which I have observed in the babbitt bearings. I find that alloys containing from about 3 per cent to about 12 per cent of silver by weight have good bearing properties, in such service as bearing linings for connecting rods in an automotive engine. I consider, however, that inthis particular service an alloy containing from 7 to 8 per cent of silver has somewhat better bearing properties than alloys having per cent silver content or 12 per cent silver content.

It should be understood that my invention is not limited to the formation of binary alloys for hearing 'alloy material. More than two metals may be alloyed and, as long as silver and cadmium are embodied in the alloy, with cadmium the principal constituent and constituting at least 80 per cent by weight of the alloy, such alloy will be within the scope of my invention. Likewise, it is not necessary that the small hard particles which are dispersed throughout the matrix be formed by the use of an excess of silver over and above that amount which enters into solid solution with the cadmium. For example, it is within the scope of my invention to utilim a metal or metals, in addition to the cadmium and silver, whichwill form small hard particles in the nature of intermetallic compounds either with the cadmium or thesilver or with both. Metals answering this description include copper, arsenic, nickel, zinc, magnesium, antimony and tin, though tin has certain undesirable properties which may render its use undesirable. One ,or more of these metals may be used in percentages preferably, though not necessarily, smaller than the percentage of silver used. When using these minor amounts of other compound-forming elements to produce the hard particles, I may correspondingly reduce the silver content,- but the silver content should be kept sufiicient to preserve the desired properties of the matrix.

It will be seen from above that I have devised an alloy for bearing lining material embodying a matrix formed primarily of cadmium, with silver in solid solution therein whereby this matrix is rendered relatively tough while retaining the desired degree of hardness. In the preferred form of my alloy, small hard particles are dispersed throughout this matrix, preferably in the form of intermetallic compounds whichiserve to make the contact and directly carry the load without impairing the conformability of the matrix.

It is also of importance that the alloy which I have produced has a higher melting point than the babbitt alloys. Likewise, the tests above referred to show that the alloypossesses a resistance to deformation by pounding which is far superior to the babbitt alloys. 9

As already pointed out, the addition of silver to the cadmium improves the casting quality of the cadmium and makes it less susceptible to oxi dation. Thus, the tendency of the cadmium to dross is overcome very materially. Likewise, the silver improves the structure and physical characterlstics of the alloy, imparting strength and hardness thereto. The silver not only increases the fluidity of the alloy with a consequent improvement in casting qualities as indicated, but it even raises the melting point slightly. Thus, I have been able to produce a bearing alloy with a base of cadmium, with its higher melting point and greater hardness than tin or lead and have imparted strength, hardness and toughness by the addition of silver which, at the same time, improves the casting qualities of the alloy. Likewise, whether my alloy be a binary alloy or whether it be forn'fed of more than two elements, I have introduced the additional metal or metals into the cadmium in sufiicient proportion to bring about dispersion of small hard particles of intermetallic compound throughout the matrix which is preferably formed by the solid solution of the silver and the cadmium.

Having thus described my invention, what I claim is:

1. A bearing material comprising essentially a matrix consisting. of cadmium with silver in solid solution therein, in combination with-small hard particles of an intermetallic compound including one of said elements dispersed throughout said matrix, the silver being present in an app eciable amount not exceeding 15 per cent by weight of the balance of the metal in the alloy.

2. A bearing alloy comprising a cadmium-rich cadmium-silver matrix, with the silver not exand a multiplicity of small hard particles of an intermetallic compound including one of said ele ments dispersed throughout said matrix.

3. A bearing alloy comprising a cadmium base with a silver content not exceeding 15 per cent of the total metal of the alloy and being in excess of that amount which will enter into solidsolution in the cadmium whereby there is formed a matrix of cadmium with silver in solid solution therein and a multiplicity or small hard particles of an intermetallic compound of cadmium and silver.

4. A bearing alloy comprising from .10 to 15 per cent of silver and the balance substantially cadmium.

5. A bearing alloy consisting of from 3 to 15 per cent of silver and the balance substantially all cadmium.

6. A bearing alloy consisting of cadmium and silver, with the silver 5 to 12 per 'cent by weight of the total and with the remainder substanmium compound dispersed throughout said matrix, the silver in said alloy being from substantially about 3 to 15 per cent by weight and the balance of the alloy being primarily of cadmium.

8. A hearing alloy comprising a matrix consisting of cadmium with silver in solid solution there- 9. A bearing alloy comprising a matrix consisting of cadmium with sliver in solid solution there in, said matrix having small hard particles of an intermetallic compound including one of said elements dispersed therethrough, the silver being present in an amount not less than .10 per cent and not exceeding'15 per cent by weight of the balance of cadmium in the alloy.

10. A bearing alloy comprising from .5 to 5% of silver and the balance substantially cadmium. 1

OSCAR E. HARDER. 

